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spr2003
16-12-2006, 10:24 AM
I'm seriously thinking to set a rack of compressors for supermarket refrigeration with two or more on-off compressors and one frequency inverter driven. This due to get always a good P.I.D. loop, coupled with elecronic expansion valves and R404a or R507 gas for both the mid and low range purpose.
Untill now i just found out hermetic or screw compressors on the european market, but i don't love them all so much.
Has anyone experience on reciprocating semi-hermetic compressors inverter equipped?
Any advice on it and how to choose, employ or run them?
Is it a good thing to buy a normal compressor and to feed it throw a commercial frequency inverter? I think it might be better to buy both the compressor and the inverter from the same producer, at least for the warranty.
Problems with lubrication and gas flow in case of reduced speed?

Thank you all, guys.

NoNickName
16-12-2006, 05:26 PM
Reciprocating do behave badly with inverter. Anyway I would suggest to buy a 230/3/50 and employ it at 400/3/100

Peter_1
20-12-2006, 11:49 PM
We have some Bitzer reciprocating racks and 2 scroll racks, some were made ourselves and they are working now for years without any problem.
We reduce the frequency to 25 Hz and increase it to 60%.

Same working principle as you mentioned: one, max two are inverter controlled, the others on/off.
Carel has a special controller for this, which controls direct the VFD's and the on/off compressors.

There's no problem with the warranty if you install you own VFD.

Bock has a compressor with a build on VFD.

Kimo Germany makes special VFD's (expensive ones) with standard software in it for refrigerantion systems. You can program the used refrigerant and the needed evaporating pressure.

Why EEV's?

spr2003
21-12-2006, 02:35 PM
Many thanks, Peter_1 :) :) :)